Method and assembly for monitoring an actuator device

ABSTRACT

A method for monitoring an actuator device of a reciprocating piston engine, wherein the actuator device is designed to actuate, particularly reversibly displace, a sliding cam device of the reciprocating piston engine, particularly substantially parallel to a camshaft of the reciprocating piston engine, with the steps S 1  Feeding of actuation energy to the actuator device, whereupon the actuator device undergoes a first state change, S 2  Monitoring of the actuator device and detection of a second state change of the actuator device, S 3  Determining of a first angle of rotation α of a camshaft or of the camshaft of the reciprocating piston engine on the basis of the second state change.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 U.S.C. 371 andclaims the benefit of PCT Application No. PCT/EP2014/073287 having aninternational filing date of 30 Oct. 2014, which designated the UnitedStates, which PCT application claimed the benefit of German PatentApplication No. 10 2013 018 263.8 filed 30 Oct. 2013, the disclosure ofeach of which are incorporated herein by reference in their entirety.

The invention relates to a method and a device for monitoring anactuator device. The invention is described in connection withreciprocating piston engines of motor vehicles.

Reciprocating piston engines can be operated according to one or moreknown cyclic processes and combustion processes. A cyclic process isassociated with certain advantages and disadvantages, particularly thedegree of exploitation of the fuel that is fed in (cost-effectiveness),the power that can be made available by the reciprocating piston engine,and the amount of pollutants produced. Two different such cyclicprocesses can require different valve lift curves for the charge cycle.Essential elements of a valve lift curve of a given intake or exhaustvalve (valve) are its opening/closing point (control times) and itsvalve travel. Using an actuator device, the charge cycle can beinfluenced by selecting one of several different valve lift curves forat least one valve, particularly as a function of the speed of thereciprocating piston engine or the gas pedal position.

It is generally perceived as very problematic if a reciprocating pistonengine is operated uneconomically for extended operating intervals.

It is the object of the present invention to enable more economicaloperation of a reciprocating piston engine.

The object is achieved by a method for monitoring an actuator deviceaccording to claim 1. Claim 7 describes a commensurate arrangement formonitoring an actuator device. Preferred developments of the inventionare the subject matter of the subclaims.

The method according to the first aspect of the invention is used tomonitor an actuator device of a reciprocating piston engine. Theactuator device is designed to actuate, particularly reversiblydisplace, a sliding cam device of the reciprocating piston engine,particularly substantially parallel to a camshaft of the reciprocatingpiston engine. The method has the following steps:

S1 Feeding of actuation energy to the actuator device, whereupon theactuator device undergoes a first state change,

S2 Monitoring of the actuator device and detection of a second statechange of the actuator device,

S3 Determining of a first angle of rotation α of a camshaft or of thecamshaft of the reciprocating piston engine on the basis of the secondstate change.

Preferably, the first state change of the actuator device consists inits change of position, particularly in its rotation and/or translation.Preferably, the first state change of the actuator device initiates areversible displacement of the sliding cam device, particularlysubstantially parallel to a camshaft.

Preferably, during step S3 with a minimum change of position Δx,particularly rotation and/or translation, of the actuator device, it isassumed that a certain first angle of rotation α of the camshaft ispresent.

Preferably, the second state change is initiated by the sliding camdevice, particularly by a peripheral extension portion of the slidingcam device.

To achieve the advantages of a certain cyclic process or combustionprocess, it is especially important that the valve lift curves,particularly the control times thereof, be adhered to. It has beenobserved that the consumption of a reciprocating piston engine isincreased, that is, that the operation thereof is less economical, inthe event of a deviation from the required or intended control times.

It is common practice to actuate a valve with a valve drive. A valvedrive can have as components a camshaft, a cam follower, avalve-clearance compensation element, and a sliding cam device, whichbears at least one eccentric cam and is slidable substantially parallelto the rotational axis of the camshaft, it being possible for thesliding cam device to be caused to rotate by the camshaft. A secondangle marking can be fastened in a torsion-proof manner to the camshaftand detected by a sensor for the angle of rotation of the camshaft.During the operation of the reciprocating piston engine, it is possible,on the basis of the detected second angle marking and the assumed orgraphic geometries of the components of the valve drive, to determine atleast one control time of a valve, for example the beginning of theopening of the valve.

However, this valve drive and its components have unavoidable tolerancesfrom the manufacturing process (manufacturing tolerances) and from theoperation of the reciprocating piston engine that may be necessary forthe proper functioning of the valve drive. As a result, unknown timedifferences can occur between the control times of a valve that areexpected based on the detected second angle marking and the actualcontrol times. It has been observed that tolerances of the component(component tolerances) can combine to bring about a noticeable deviationof the actual control times from the required or intended control times.

With the method according to the first aspect, the first angle ofrotation α of a camshaft or of the camshaft can be detected on the basisof the second state change of the actuator device. Preferably, thesecond state change of the actuator device is initiated by the slidingcam device.

With the method according to the first aspect, the first angle ofrotation α of a camshaft or of the camshaft can be detected with greateraccuracy and the resolution of the rotation angle detection can beincreased.

In particular, with the method according to the first aspect, atolerance error in the rotation angle detection can be identified and,particularly, corrected.

A closer mechanical interrelation exists between the state changes ormovements of the actuator device and the movements of the associatedvalve than between the movements of the valve and of the second anglemarking of the camshaft. The first angle of rotation α can be determinedwith greater accuracy with the method according to the invention thanthrough detection of the second angle marking of the camshaft,particularly if several component tolerances have a less pronouncedimpact. Preferably, tolerances of the camshaft and of its second anglemarking can be eliminated. As a result, required or intended controltimes can be better adhered to and the underlying object achieved. Towit, in certain combustion processes, such as the Miller cycle, forexample, a two to three percent tolerance in the determination of theposition of the eccentric cam leads to a significant charge differenceof the piston of up to 30%—depending on the respective operatingpoint—and to poorer mixture preparation, errors in the charge cycle, andconsumption drawbacks.

In terms of the invention, an actuator device is to be understood as adevice that is used particularly to actuate a sliding cam device of thereciprocating piston engine, particularly for the reversibledisplacement of the sliding cam device, particularly substantiallyparallel to a camshaft of the reciprocating piston engine. The actuatordevice is designed to exert a force component on the sliding cam devicefrom time to time substantially parallel to the camshaft of thereciprocating piston engine. Through the application of the forcecomponent, the sliding cam device can be reversibly displacedsubstantially parallel to the camshaft. The actuator device is designedto be displaced or moved with respect to a second longitudinal axis B.Preferably, the actuator device is designed to rotate about the secondlongitudinal axis B and/or to move translationally substantiallyparallel to the second longitudinal axis B.

Preferably, the actuator device is embodied with a machine element,especially preferably with a pin, bolt, pin-shaped portion, finger orrotating lever. Preferably, the actuator device is embodied with ametal. Preferably, the actuator device has a wear-reducing orfriction-reducing coating in some portions.

A state change of the actuator device is to be understood in terms ofthe invention particularly as a displacement, positional change ormovement of the actuator device, preferably in relation to the secondlongitudinal axis B. During the operation of the reciprocating pistonengine, the actuator device repeatedly undergoes state changes,particularly for the purpose of actuating or displacing the sliding camdevice, particularly initiated by the sliding cam device. To initiatethe first state change, kinetic energy is fed to the actuator device.Preferably, a displacement of the sliding cam device can initiate thefirst state change. Preferably, in order to initiate the second statechange, a force component that is outwardly directed and radial to therotational axis A of the camshaft is applied by the sliding cam deviceto the actuator device.

In terms of the invention, a sliding cam device is to be understood as adevice that

-   -   is used particularly for the at least indirect actuation or        opening of at least one intake or exhaust valve (valve) of the        reciprocating piston engine, and/or    -   is used particularly for the at least indirect loading of the        valve with a force component in the direction of an associated        combustion chamber of the reciprocating piston engine or along a        valve shaft, and/or    -   is used particularly for the temporary loading of the actuator        device with a force that is outwardly directed and radial to the        rotational axis of the camshaft, and/or    -   is used particularly for initiating the second state change of        the actuator device.

The sliding cam device is designed to rotate at least intermittentlywith the camshaft. The sliding cam device is designed to be reversiblydisplaced or slid along the camshaft or its rotational axis. The slidingcam device has at least one or two cams on an outer surface orcircumferential surface that are used for the at least indirectactuation of the valve or the indirect loading of the valve with theforce component. Preferably, the sliding cam device has two such camsthat can effect different valve lift curves.

Preferably, the sliding cam device has a substantially cylindrical shapewith an interior space, the camshaft being capable of extending throughthis interior space. Especially preferably, the sliding cam device hasin its interior space a coupling element for connecting in a frictionalor form-fitting manner to the camshaft.

Preferably, the sliding cam device has at least one portion on acircumferential surface, preferably at least one peripheral extensionportion, that is used for the occasional loading of the actuator devicewith a force component that is outwardly directed and radial to therotational axis. The peripheral extension portion is used for thetemporary loading of the actuator device with a force that is outwardlydirected and radial to the rotational axis A of the camshaft. Theperipheral extension portion is arranged on a circumferential surface ofthe sliding cam device. Preferably, the peripheral extension portion isembodied with an ascending flank or ramp, the flank being capable offorcing the actuator device away from the rotational axis A. Especiallypreferably, the flank or ramp transitions uniformly or continuously inthe circumferential direction into the remaining circumferentialsurface.

Preferably, the sliding cam device has a first angle marking that can bedetected by a sensor, which can be used to detect the second angle ofrotation β. Especially preferably, the first angle marking is arrangedon a circumferential surface or front face of the sliding cam device.

In terms of the invention, a camshaft is to be understood as a devicethat is used particularly at least indirectly for the actuation of atleast one of the valves of the reciprocating piston engine, which isused particularly for guiding and driving the sliding cam device. Thecamshaft can rotate about its rotational axis A, the camshaft preferablybeing aligned substantially parallel to the crankshaft of thereciprocating piston engine. The camshaft can be driven at leastindirectly by the crankshaft. Preferably, the camshaft has a secondangle marking that can be detected by a sensor and can indicate theangle of rotation of the camshaft (first angle of rotation α).Preferably, the camshaft has on a circumferential surface at least onecoupling element for connecting in a frictional and/or form-fittingmatter to the sliding cam device, the coupling element being usedparticularly for driving the sliding cam device, and the couplingelement being used particularly to guide the sliding cam device duringits displacement of the rotational axis.

In terms of the invention, the second angle of rotation β is a measurefor the position and rotation of the sliding cam device about therotational axis A of the camshaft. Preferably, the second angle ofrotation β is correlated with a beam 0 (zero beam), which is alignedsubstantially perpendicularly to the rotational axis A. Here, the secondangle of rotation β is determined in relation to the zero beam on thebasis of the second state change.

In terms of the invention, the first angle of rotation α is a measurefor the position and rotation of the camshaft about its rotational axisA. Preferably, the first angle of rotation α is correlated with the zerobeam. Here, the first angle of rotation α is determined in relation tothe zero beam, particularly by calculation, on the basis of the secondstate change.

In terms of the invention, the third angle of rotation ε is a measurefor the position and rotation of the camshaft about its rotational axisA. Preferably, the third angle of rotation ε is correlated with the zerobeam. Here, the third angle of rotation ε is determined on the basis ofthe detected second angle marking of the camshaft. Particularly as aresult of component tolerances or manufacturing tolerances, the thirdangle of rotation ε can deviate from the first angle of rotation α ofthe same camshaft.

In terms of the invention, the fourth angle of rotation ζ is a measurefor the position and rotation of the crankshaft about its rotationalaxis. Preferably, the fourth angle of rotation ζ is correlated with abeam that is arranged substantially parallel to the zero beam.

The differential angles γ₁, γ₂, γ₃ are each calculated with differencesfrom two of the aforementioned angles of rotation.

In terms of the invention, the position x is to be understood as ameasure for a certain position of the actuator device. The position xcan refer to a distance or to an angle in relation to a reference,particularly depending on whether the actuator device is designed tomove rotationally or translationally in relation to the secondlongitudinal axis B.

A predetermined change of position Δx is to be understood in terms ofthe invention as a minimum positional change of the actuator device,which is understood as the second state change of the actuator device.Insofar as the actuator device is designed to move translationally inrelation to the second longitudinal axis B, a minimum path is understoodas the second state change. Insofar as the actuator device is designedto rotate in relation to the second longitudinal axis B, a minimum angleis understood as the second state change. Preferably, the predeterminedchange of position Δx is a few millimeters or a few degrees [°] or onlyfractions thereof.

According to a preferred development, the actuation energy is fedelectromagnetically, inductively or electrostatically. This preferreddevelopment can particularly offer the advantage that the movementthrough the first state change can be initiated in a contactless manner.This preferred development can particularly offer the advantage that thecontrol for moving through the first state change can be doneelectrically. This preferred development can particularly offer theadvantage that the initiation of the first state change can occur withreduced wear.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, the second statechange is detected electromagnetically, inductively, electrostatically,capacitatively or optoelectronically. This preferred development canparticularly offer the advantage that the second state change can bedetected with reduced wear. This preferred development can particularlyoffer the advantage that the event of the second state change can befurther processed by electronic means.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, the second statechange is detected by means of a change of position, particularly atranslation or a rotation, particularly in relation to a secondlongitudinal axis B, of the actuator device. Preferably, a minimum orpredetermined change of position of the actuator device is processed orunderstood as its second state change. This preferred development canparticularly offer the advantage that the second state change can bedetected with a distance measurement device or angle measuring device.This preferred development can particularly offer the advantage that theevent of the second state change can be further processed by electronicmeans.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, the first angle ofrotation α is determined on the basis of a predetermined change ofposition Δx or minimum change of position of the actuator device. Thispreferred development can particularly offer the advantage that small,simple and/or economical sensors can be used to detect the second statechange.

A preferred development, which can be advantageously combined with oneof the abovementioned developments, has the following steps:

S4 Determining of a second angle of rotation β of the sliding cam deviceon the basis of the second state change or on the basis ofthe—particularly predetermined—change of position Δx of the actuatordevice, particularly wherein the apex of the second angle of rotation βlies on a rotational axis A of the camshaft,

S5 Linking of the second angle of rotation β and first angle of rotationα at a first differential angle γ₁.

Preferably, during step S4, with a minimum change of position Δx of theactuator device, it is assumed that a certain second angle of rotation βof the sliding cam device is present.

Preferably, during step S5, the difference between the second angle ofrotation β and the first angle of rotation α is formed.

Preferably, the first differential angle is linked with an engine-speedchange dζ/dt of the crankshaft, particularly through subtraction.Particularly in the case of decreasing or increasing speeds of thecrankshaft, a relative movement between the sliding cam device and thecamshaft can occur, so the first differential can fluctuate during theoperation of the reciprocating piston engine.

This preferred development can particularly offer the advantage thatchanges in the timing of at least one of the two angles of rotationduring the operation of the reciprocating piston engine can be detected.This preferred development can particularly offer the advantage that theinfluence of the clearance fit between sliding cam device and camshaftcan be taken into account in determining the first differential angle.This preferred development can particularly offer the advantage that thefirst differential angle can be used as an indication of tolerances inthe valve drive.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, a first anglemeasuring device is connected to the camshaft in a rotationally fixedmanner. A combination of a second angle marking that is connected to thecamshaft in a rotationally fixed manner and a sensor for detecting thissecond angle marking that is stationary with respect to the rotatingcamshaft is also regarded as a first angle measuring device in terms ofthe invention. The preferred development has the following steps:

S6 Detecting of a third angle of rotation ε of the camshaft with thefirst angle measuring device,

S7 Linking, particularly subtracting, of the second angle of rotation βand/or of the first angle of rotation α with the third angle of rotationε, particularly at a second differential angle γ₂.

Preferably, the second differential angle is linked with an engine-speedchange dζ/dt of the crankshaft, particularly through subtraction.Particularly in the case of decreasing or increasing speeds of thecrankshaft, a relative movement between the sliding cam device and thecamshaft can occur, so the second differential angle can fluctuateduring the operation of the reciprocating piston engine.

This preferred development can particularly offer the advantage thatchanges in the timing of at least one of the angles of rotation duringthe operation of the reciprocating piston engine can be detected. Thispreferred development can particularly offer the advantage that theinfluence of the clearance fit between sliding cam device and camshaftcan be taken into account in determining the second differential angle.This preferred development can particularly offer the advantage that thesecond differential angle can be used as an indication of tolerances inthe valve drive. This preferred development can particularly offer theadvantage that a defect of one of the sensors or of the first anglemeasuring device can be deduced from an unusual differential angle.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, a second anglemeasuring device is connected to the crankshaft of the reciprocatingpiston engine in a rotationally fixed manner. A combination of an anglemarking that is connected to the crankshaft in a rotationally fixedmanner and a sensor for detecting this angle marking that is stationarywith respect to the rotating crankshaft is also regarded as a secondangle measuring device in terms of the invention. The preferreddevelopment has the following steps:

S8 Detecting of a fourth angle of rotation ζ of the crankshaft with thesecond angle measuring device (22 a),

S9 Linking of the second angle of rotation β and/or of the first angleof rotation α with the fourth angle of rotation ζ, particularly at athird differential angle γ₃.

Preferably, the third differential angle is linked with an engine-speedchange dζ/dt of the crankshaft, particularly through subtraction.Particularly in the case of decreasing or increasing speeds of thecrankshaft, a relative movement between the sliding cam device and thecamshaft can occur, so the third differential angle can fluctuate duringthe operation of the reciprocating piston engine.

This preferred development can particularly offer the advantage thatchanges in the timing of at least one of the angles of rotation duringthe operation of the reciprocating piston engine can be detected. Thispreferred development can particularly offer the advantage that theinfluence of the clearance fit between sliding cam device and camshaftcan be taken into account in determining the third differential angle.This preferred development can particularly offer the advantage that thethird differential angle can be used as an indication of tolerances,particularly in the valve drive. This preferred development canparticularly offer the advantage that a defect of one of the sensors orof the second angle measuring device can be deduced from an unusualdifferential angle.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, the camshaft hasan adjustment mechanism that is designed to set an angle-of-rotationposition of the camshaft relative to the crankshaft. The preferreddevelopment has the following step:

S10 Setting of the angle-of-rotation position on the basis of the firstdifferential angle γ₁, the second differential angle γ₂, or the thirddifferential angle γ₃.

Preferably, step S10 occurs repeatedly or intermittently during theoperation of the reciprocating piston engine.

This preferred development can particularly offer the advantage thatincreasing wear of the valve drive can be taken into account,particularly in order to enable more economical operation of thereciprocating piston engine. This preferred development can particularlyoffer the advantage that it is possible to react to thermal influenceson the valve drive, particularly in order to enable more economicaloperation of the reciprocating piston engine.

The underlying object is also achieved by a computer program containinginstructions, with the instructions causing the control device toexecute a method according to the first aspect of the invention oraccording to a preferred development when carried out by a controldevice.

The underlying object is also achieved by a computer-readable medium onwhich the aforementioned computer program is stored.

The arrangement according to the second aspect of the invention is usedto monitor an actuator device of a reciprocating piston engine,particularly to execute the method according to the first aspect of theinvention or to execute one of its preferred developments. Thearrangement has:

-   -   a camshaft that can rotate about a rotational axis A,    -   a sliding cam device that can be displaced substantially        parallel to the rotational axis A and has a peripheral extension        portion on a circumferential surface,    -   an actuator device that is designed to actuate or displace the        sliding cam device and can undergo a second state change,    -   a second measuring device that is designed to detect the second        state change and is particularly capable of determining a first        angle of rotation α of the camshaft on the basis of the second        state change,    -   the peripheral extension portion being designed to load the        actuator device with at least one force component outwardly        directed and radial to the rotational axis A.

Preferably, the sliding cam device is embodied with a peripheralextension portion that is used to initiate the second state change.

To achieve the advantages of a certain cyclic process or combustionprocess, it is especially important that the valve lift curves,particularly the control times thereof, be adhered to. It has beenobserved that the consumption of a reciprocating piston engine isincreased, that is, that the operation thereof is less economical, inthe event of a deviation from the required or intended control times.

It is common practice to actuate a valve with a valve drive. A valvedrive can have as components a camshaft, a cam follower, avalve-clearance compensation element, and a sliding cam device thatbears at least one eccentric cam, is slidable substantially parallel tothe rotational axis of the camshaft, and can be caused to rotate by thecamshaft. A second angle marking can be fastened in a torsion-proofmanner to the camshaft and detected by a sensor for the angle ofrotation of the camshaft. During the operation of the reciprocatingpiston engine, it is possible, on the basis of the detected second anglemarking and the assumed or graphic geometries of the components of thevalve drive, to determine at least one control time of a valve, forexample the beginning of the opening of the valve.

However, this valve drive and its components have unavoidable tolerancesfrom the manufacturing process (manufacturing tolerances) and from theoperation of the reciprocating piston engine that may be necessary forthe proper functioning of the valve drive. As a result, unknown timedifferences can occur between the control times of a valve that areexpected based on the detected second angle marking and the actualcontrol times. It has been observed that tolerances of the component(component tolerances) can combine to bring about a noticeable deviationof the actual control times from the required or intended control times.

With the arrangement according to the second aspect, the first angle ofrotation α of a camshaft or of the camshaft can be detected on the basisof the second state change of the actuator device. Preferably, thesecond state change of the actuator device is initiated by the slidingcam device.

A closer mechanical interrelation exists between the state changes ormovements of the actuator device and the movements of the associatedvalve than between the movements of the valve and of the second anglemarking of the camshaft. The first angle of rotation α can be determinedwith greater accuracy with the method according to the invention thanthrough detection of the second angle marking of the camshaft,particularly if several component tolerances have a less pronouncedimpact. Preferably, tolerances of the camshaft and of its second anglemarking can be eliminated. As a result, required or intended controltimes can be better adhered to and the underlying object achieved.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, the actuatordevice has a first coupling element that is designed to intermittentlyload the sliding cam device with a force component substantiallyparallel to the rotational axis A, which is designed to change position,particularly to move translationally or to rotate, particularly inrelation to a second longitudinal axis B of the actuator device, and hasa drive element that is designed to intermittently load the couplingelement with a force component substantially perpendicular to therotational axis A.

Preferably, the first coupling element device is embodied with a machineelement, especially preferably with a projection, pin, bolt, pin-shapedportion, finger, roller, rotor, lever or rotating lever. Preferably, thefirst coupling element is embodied with a metal. Preferably, the firstcoupling element has a wear-reducing or friction-reducing coating insome portions. Preferably, the first coupling element is designedparticularly to contact the sliding cam device or its peripheralextension portion in a form-fitting manner. Preferably, the firstcoupling element is embodied with or connectable to a Hall sensor.Preferably, the first coupling element is reversibly displaceablesubstantially parallel to the second longitudinal axis B. Alternatively,the first coupling element is designed so as to reversibly rotate aboutthe second longitudinal axis B.

Preferably, the drive element is designed to apply force mechanically,especially preferably electromagnetically, electrostatically orinductively, to the first coupling element. Preferably, the driveelement is embodied with an electrical coil, the coil being especiallypreferably capable of receiving the first coupling element at leastpartially. Preferably, the drive element or the coil, especiallypreferably during step S1, can be fed current, especially preferably inorder to initiate the first state change of the first coupling elementor the displacement thereof. Preferably, the drive element or the coil,especially preferably during step S2, can be used to monitor a change ofposition of the first coupling element, particularly in a currentlessmanner.

This preferred development can particularly offer the advantage that thefirst coupling element can be adapted to the installation spaceavailable in the region of the cylinder head, to the operatingtemperatures, to the material of the sliding cam device, to the speedsof the camshaft and/or to the opposing forces between the sliding camdevice under the camshaft. This preferred development can particularlyoffer the advantage that the drive element can be used for thecontactless actuation of or application of force to the first couplingelement. This preferred development can particularly offer the advantagethat the drive element can be used for the contactless detection of achange of position or second state change of the first coupling element.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, the secondmeasuring device is designed so as to detect the second state change orchange of position electromagnetically, inductively, electrostatically,capacitatively or optoelectronically, and/or it is integrally formedwith the drive element, and/or it is embodied with a Hall sensor. Thispreferred development can particularly offer the advantage that thedetection of the second state change or change of position of theactuator device can occur in a substantially contactless manner. Thispreferred development can particularly offer the advantage that thedetected state change or change of position of the actuator device canbe further processed electrically.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, the arrangementhas a first measuring device that is embodied with an electromagnetic,inductive, electrostatic, capacitative or optoelectronic sensor, that isdesigned to detect the second angle of rotation β, the third angle ofrotation ε or the fourth angle of rotation ζ, and that is preferablyembodied with an ohmic sensor, inductive sensor, capacitative sensor,Hall sensor or with an optoelectronic sensor. Preferably, the firstmeasuring device is used to detect an angle marking that is connected ina rotationally fixed manner to the sliding cam device, the camshaft orthe crankshaft. This preferred development can particularly offer theadvantage that the first angle of rotation α can be compared to anotherdetected angle of rotation of the reciprocating piston engine. Thispreferred development can particularly offer the advantage that a defectof the arrangement for monitoring the actuator device, particularly adefect of the second measuring device, can be noticed more easily.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, the arrangementhas one of these first angle measuring devices that is connected to thecamshaft in a rotationally fixed manner and is designed to detect thethird angle of rotation ε of the camshaft. A combination of a secondangle marking that is connected to the camshaft in a rotationally fixedmanner and a sensor for detecting this second angle marking that isstationary with respect to the rotating camshaft is also regarded as afirst angle measuring device in terms of the invention. This preferreddevelopment can particularly offer the advantage that the first angle ofrotation α can be compared to another detected angle of rotation of thereciprocating piston engine. This preferred development can particularlyoffer the advantage that a defect of the arrangement for monitoring theactuator device, particularly a defect of the second measuring device,can be noticed more easily.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, the arrangementhas one of these second angle measuring devices that is connected to thecrankshaft in a rotationally fixed manner and is designed to detect thefourth angle of rotation ζ. A combination of an angle marking that isconnected to the crankshaft in a rotationally fixed manner and a sensorfor detecting this angle marking that is stationary with respect to therotating camshaft is also regarded as a second angle measuring device interms of the invention. This preferred development can particularlyoffer the advantage that the first angle of rotation α can be comparedto another detected angle of rotation of the reciprocating pistonengine. This preferred development can particularly offer the advantagethat a defect of the arrangement for monitoring the actuator device,particularly a defect of the second measuring device, can be noticedmore easily.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, the sliding camdevice has on a circumferential surface a guide groove arrangement withat least one, two or more guide grooves, the guide groove arrangementbeing designed to intermittently guide the actuator device or the firstcoupling element thereof substantially in the manner of a slotted guide,the guide groove arrangement being embodied with the peripheralextension portion, and the guide groove arrangement preferably havingtwo intersecting guide grooves.

Preferably, at least one of the guide grooves of the guide groovearrangement has one of these peripheral extension portions. Preferably,at least one of the guide grooves of the guide groove arrangementextends along at least a portion of the circumferential surface of thesliding cam device. Preferably, the guide groove arrangement is embodiedwith two intersecting guide grooves according to DE 10 2012 012 064.

This preferred development can particularly offer the advantage that theforce transmission between the actuator device and the sliding camdevice is improved. This preferred development can particularly offerthe advantage that the displacement of the sliding cam device isreliable at higher camshaft speeds. This preferred development canparticularly offer the advantage that the second state change of orapplication of force to the actuator device can occur through the bottomsurface of one of the guide grooves of the guide groove arrangement.

According to a preferred development, which can be advantageouslycombined with one of the abovementioned developments, the arrangementhas an adjustment mechanism that is designed to set an angle-of-rotationposition of the camshaft relative to the crankshaft, and with a controldevice that is designed to control the adjustment mechanism on the basisof the second state change, the change of position of the actuatordevice, the first differential angle γ₁, the second differential angleγ₂ or the third differential angle γ₃, preferably to set theangle-of-rotation position.

Preferably, the adjustment mechanism is disposed between a drive wheel,particularly embodied as a gearwheel, belt pulley or sprocket, which canbe driven at least indirectly by the crankshaft, and the camshaft. Theadjustment mechanism is designed to reversibly rotate the drive wheel inrelation to the camshaft.

This preferred development can particularly offer the advantage that, byadjusting the angle-of-rotation position to tolerances of the componentsof the valve drive, it is possible to react to manufacturing tolerancesor play between the crankshaft and the camshaft. This preferreddevelopment can particularly offer the advantage that a differencebetween an actual control time and the required or intended control timecan be reduced.

According to a third aspect of the invention, the reciprocating pistonengine has one of these arrangements according to the second aspect orone of the preferred developments thereof.

To achieve the advantages of a certain cyclic process or combustionprocess, it is especially important that the valve lift curves,particularly the control times thereof, be adhered to. It has beenobserved that the consumption of a reciprocating piston engine isincreased, that is, that the operation thereof is less economical, inthe event of a deviation from the required or intended control times.

It is common practice to actuate a valve with a valve drive. A valvedrive can have as components a camshaft, a cam follower, avalve-clearance compensation element, and a sliding cam device thatbears at least one eccentric cam, is slidable substantially parallel tothe rotational axis of the camshaft, and can be caused to rotate by thecamshaft. A second angle marking can be non-rotatably fastened to thecamshaft and detected by a sensor for the angle of rotation of thecamshaft. During the operation of the reciprocating piston engine, it ispossible, on the basis of the detected second angle marking and theassumed or graphic geometries of the components of the valve drive, todetermine at least one control time of a valve, for example thebeginning of the opening of the valve.

However, this valve drive and its components have unavoidable tolerancesfrom the manufacturing process (manufacturing tolerances) and from theoperation of the reciprocating piston engine that may be necessary forthe proper functioning of the valve drive. As a result, unknown timedifferences can occur between the control times of a valve that areexpected based on the detected second angle marking and the actualcontrol times. It has been observed that tolerances of the component(component tolerances) can combine to bring about a noticeable deviationof the actual control times from the required or intended control times.

With the reciprocating piston engine according to the third aspect, thefirst angle of rotation α of a camshaft or of the camshaft can bedetected on the basis of the second state change of the actuator device.Preferably, the second state change of the actuator device is initiatedby the sliding cam device.

A closer mechanical interrelation exists between the state changes ormovements of the actuator device and the movements of the associatedvalve than between the movements of the valve and of the second anglemarking of the camshaft. The first angle of rotation α can be determinedwith greater accuracy with the method according to the invention thanthrough detection of the second angle marking of the camshaft,particularly if several component tolerances have a less pronouncedimpact. Preferably, tolerances of the camshaft and of its second anglemarking can be eliminated. As a result, required or intended controltimes can be better adhered to and the underlying object achieved.

Additional advantages, features and possible applications of the presentinvention follow from the following description in conjunction with thefigures.

FIG. 1 shows a schematic representation of a section through a camshaftand through a sliding cam device to show different angles,

FIG. 2 shows a diagram of the method according to the first aspect ofthe invention,

FIG. 3 shows a diagram of a preferred development of the methodaccording to the first aspect of the invention,

FIG. 4 shows a diagram of another preferred development of the methodaccording to the first aspect of the invention,

FIG. 5 shows a diagram of another preferred development of the methodaccording to the first aspect of the invention,

FIG. 6 shows a schematic representation of an arrangement according tothe second aspect of the invention at different points in time,

FIG. 7 shows another schematic representation of an arrangementaccording to the second aspect of the invention at different points intime,

FIG. 8 shows a schematic representation of preferred developments of thearrangement according to the invention,

FIG. 9 shows a schematic representation of another preferred developmentof the arrangement according to the invention,

FIG. 1 shows a schematic representation of a section through a camshaft1 and through a sliding cam device 3 to show different angles.

A sliding cam device 3 is embodied here so as to be substantially hollowand cylindrical. A camshaft 1 extends through the hollow space of thesliding cam device 3. However, this design of the sliding cam device 3is not imperative for the technical effect of the invention.

Starting from a zero beam, which is shown as a horizontal line andmarked with “0,” the second angle of rotation β of the sliding camdevice, the first angle of rotation α of the camshaft 1 determined instep S3, and the measured third angle of rotation ε of the camshaft 1are shown. The sliding cam device 3 has a first angle marking throughwhich the second leg of the second angle of rotation β passes. It is notimperative that this first angle marking be arranged on acircumferential surface of the sliding cam device 3. The camshaft 1 hasa second angle marking—represented by a solid line—through which thesecond leg of the third angle of rotation ε passes. It is not imperativethat this second angle marking be arranged on a front face of thecamshaft 1.

A thinner, broken line shows the position of the second angle marking ofthe camshaft 1 that the second angle marking would ideally assume butthat the second angle marking does not assume as a result of acharacteristic measure of tolerance of the manufacturing process.

To clarify the fourth angle of rotation ζ, the crankshaft 21 is alsoshown with its own angle marking that does not, however, belong to thearrangement of the second aspect.

FIG. 2 shows a diagram of the method according to the first aspect ofthe invention.

During step S1, an actuation energy is fed to the actuator device 14,upon which the actuator device 14 undergoes a first state change.Preferably, the first state change of the actuator device 14 consists inits change of position, particularly in its rotation and/or translationin relation to a second longitudinal axis B of the actuator device 14.Preferably, the first state change of the actuator device 14 initiates areversible displacement of the sliding cam device 3, particularlysubstantially parallel to a camshaft 1 of the reciprocating pistonengine.

During step S2, the actuator device 14 is monitored and a second statechange of the actuator device 14 is detected. Preferably, the secondstate change of the actuator device 14 consists in the change ofposition thereof. Preferably, the second state change is initiated bythe sliding cam device 3, especially preferably by the peripheralextension portion thereof.

During step S3, the first angle of rotation α of a camshaft or of thecamshaft 1 of the reciprocating piston engine is detected on the basisof the second state change of the actuator device 14. Preferably, apredetermined change of position of the actuator device 14 is detectedand particularly processed as an indication of the second state changeof the actuator device 14.

It is with this method that the underlying object is achieved.

FIG. 3 shows a diagram of a preferred development of the methodaccording to the first aspect of the invention. In addition to steps S1,S2 and S3, steps S4 and S5 are carried out.

During step S4, the second angle of rotation β of the sliding cam device3 is determined on the basis of the second state change or on the basisof the—particularly predetermined—change of position Δx of the actuatordevice 14, particularly wherein the apex of the second angle of rotationβ lies on the rotational axis A of the camshaft 1.

During step S5, the second angle of rotation β and first angle ofrotation α are linked with a first differential angle γ₁.

Preferably, step S10 follows step S5; during step S10, however, theangle-of-rotation position of the camshaft 1 in relation to thecrankshaft 21 is set on the basis of the first differential angle γ₁,especially preferably by a control device 7.

FIG. 4 shows a diagram of another preferred development of the methodaccording to the first aspect of the invention. In addition to steps S1,S2 and S3, steps S6 and S7 are carried out.

During step S6, the third angle of rotation ε of the camshaft 3 isdetected with a first angle measuring device 22.

During step S7, the second angle of rotation β and/or the first angle ofrotation α are linked with the third angle of rotation ε at a seconddifferential angle γ₂.

Preferably, step S10 follows step S7; during step S10, however, theangle-of-rotation position of the camshaft 1 in relation to thecrankshaft 21 is set on the basis of the second differential angle γ₂,especially preferably by a control device 7.

FIG. 5 shows a diagram of another preferred development of the methodaccording to the first aspect of the invention. In addition to steps S1,S2 and S3, steps S8 and S9 are carried out.

During step S8, the fourth angle of rotation ζ of the crankshaft isdetected with the second angle measuring device 4.

During step S9, the second angle of rotation β and/or the first angle ofrotation α are linked with the fourth angle of rotation ζ, particularlyat a third differential angle γ₃.

Preferably, step S10 follows step S7; during step S10, however, theangle-of-rotation position of the camshaft 1 in relation to thecrankshaft 21 is set on the basis of the third differential angle γ₃,especially preferably by a control device 7.

FIG. 6 shows a schematic representation of an arrangement according tothe second aspect of the invention at different points in time. Thearrangement has the camshaft 1, the sliding cam device 3, the actuatordevice 14 and a second measuring device 6, particularly an incrementalencoder. The sliding cam device 3 has the peripheral extension portion10. The actuator device 14 is embodied with a bolt or pin that isdesigned to move translationally in relation to the longitudinal axis B.

Only for the purpose of clarifying the first angle of rotation α, asecond angle marking is shown on the camshaft 1 with a broken line. Thissecond angle marking of the camshaft 1 is not required for the methodaccording to the first aspect and for the arrangement according to thesecond aspect.

The sliding cam device 3 can be displaced substantially parallel to therotational axis A, which extends substantially perpendicular to thedrawing plane. The sliding cam device 3 can preferably be connected tothe camshaft 1 in a frictional and/or force-fitting manner. The camshaft1 is designed to intermittently drive the sliding cam device 3 such thatit rotates.

The arrangement following step S1 is shown in the upper half of FIG. 6.As the sliding cam device 3 continues to rotate, the actuator device 14is to be loaded by the sliding cam device 3 with a force component alongthe arrow drawn next to the actuator device 14. In the arrangementillustrated in the upper half of FIG. 6, the actuator device 14 iscurrently being monitored.

The arrangement following step S2 is shown in the lower half of FIG. 6.The camshaft 1 and the sliding cam device 3 have rotated together a fewdegrees around the rotational axis A. The actuator device 14 has beendisplaced by the distance Δx. For the method according to the firstaspect and the arrangement according to the second aspect, it issufficient for the predetermined change of position Δx to be only a fewmillimeters or degrees or even only fractions thereof.

The second measuring device 6 has detected the second state change ofthe actuator device 14 as a change of position. The first angle ofrotation α has been determined from the predetermined change of positionΔx and from the second state change of the actuator device 14.

FIG. 7 shows a schematic representation of another arrangement accordingto the second aspect of the invention at different points in time.Unlike in FIG. 6, the actuator device 14 is embodied with a lever thatcan rotate about the second longitudinal axis B. In this embodiment, thechange of position Δx of the actuator device 14, which is to be regardedas an indication of its second state change, occurs as a rotation aboutthe second longitudinal axis B.

In the lower half of FIG. 7, the second state change of the actuatordevice 14 has been detected by the second measuring device 6. Moreover,the first angle of rotation α has been determined on the basis of thesecond state change.

FIG. 8 shows a schematic representation of preferred developments of thearrangement according to the invention. In deviation from FIG. 6, whatthese developments have in common is that the angle measuring device fordetecting the angle of rotation ε of the camshaft is embodied with asecond angle marking 4 and a sensor 5. The second angle marking 4 isconnected in a rotationally fixed manner to the front face of thecamshaft 1.

The two upper illustrations (FIGS. 8a, 8b ) correspond substantially tothe preferred development according to FIG. 6. The peripheral extensionportion 10 of the sliding cam device 3 is marked in the uppermostillustration (FIG. 8a ).

Unlike in FIG. 6, in the lower illustration (FIG. 8c ), the actuatordevice is embodied with the first coupling element 14 and the driveelement 13. The second measuring device 6 is embodied with an electricalcoil and is integrally formed with the drive element 13. Preferably, theelectrical coil 13 can be intermittently traversed by a current,especially preferably when the actuator device 14 is to be loaded with aforce component substantially radially to the rotational axis A.Preferably, a current can be induced intermittently in the electricalcoil 13, especially preferably when the first coupling element 14penetrates more deeply into the coil 13.

FIG. 9 shows a schematic representation of another preferred developmentof the arrangement according to the invention. Compared to theembodiment according to FIG. 6, the following are additionally depicted:the crankshaft 21, an angle measuring device 4, 5 for detecting thefourth angle of rotation ζ, drive device with which the crankshaft 21can drive the camshaft 1 here, the control device 7 and the adjustmentmechanism 16. An angle marking 4 is connected in a rotationally fixedmanner to the front face of the crankshaft 21. A first measuring device5 is used to detect the angle marking 4.

The control device 7 can receive and process signals of the secondmeasuring device 6 as well as of the first measuring device 5. Thecontrol device 7 can link together the signals of the first measuringdevice 5 and second measuring device 6, particularly at a differentialangle γ. The control device 7 can control the adjustment mechanism 16 onthe basis of the differential angle γ. For this purpose, the controldevice 7 is signal-connected to the first measuring device 5, the secondmeasuring device 6 and the adjustment mechanism 16, as is shown by thedashed signal lines.

REFERENCE SYMBOLS

1 camshaft

2 first angle marking of the sliding cam device

3 sliding cam device

4 second angle marking of the camshaft

5 first measuring device

6 second measuring device

7 first control device

9 sensor

10 peripheral extension portion

13 drive element

14 actuator device

15 guide groove arrangement

16 adjustment mechanism

21 crankshaft

22, 22 a angle measuring device

α first angle of rotation

β second angle of rotation γ₁, γ₂, γ₃ differential angles

ε third angle of rotation of the camshaft, measured

ζ fourth angle of rotation of the crankshaft

A rotational axis of the camshaft

B second longitudinal axis of the actuator device

x position of the actuator device and of the first coupling element

Δx change of position of the actuator device and of the first couplingelement

The invention claimed is:
 1. A method for determining an angle ofrotation of a camshaft of a reciprocating piston engine, comprising:providing the reciprocating piston engine with an actuator device, thecamshaft, and a sliding cam device positioned substantially parallel tothe camshaft, wherein the actuator device actuates by reversiblydisplacing the sliding cam device of the reciprocating piston engine,feeding of actuation energy to the actuator device, whereupon theactuator device undergoes a first state change, monitoring of theactuator device, detecting a second state change of the actuator device,determining of a first angle of rotation a of the camshaft of thereciprocating piston engine on the basis of the second state change ofthe actuator device, determining of a second angle of rotation β of thesliding cam device on the basis of the second state change or on thebasis of a predetermined change of position of the actuator device,wherein an apex of the second angle of rotation β lies on a rotationalaxis (A) of the camshaft, and linking of the second angle of rotation βand first angle of rotation a at a first differential angle γ₁.
 2. Themethod as set forth in claim 1, wherein at least one of the following istrue: the actuation energy is fed in electromagnetically, inductively orelectrostatically, the second state change is detectedelectromagnetically, inductively, electrostatically, capacitatively oroptoelectronically, the second state change is detected as a change ofposition of the actuator device, wherein the change of position is atranslational movement or rotation in relation to a second longitudinalaxis (B), and the first angle of rotation a is determined on the basisof the predetermined change of position of the actuator device.
 3. Themethod as set forth in claim 1, wherein the camshaft has an adjustmentmechanism that is designed to set an angle-of-rotation position of thecamshaft relative to a crankshaft, further comprising: setting of theangle-of-rotation position on the basis of the first differential angleγ₁, a second differential angle γ₂, or a third differential angle γ₃. 4.An arrangement for monitoring an actuator device of a reciprocatingpiston engine, wherein the arrangement comprises: a camshaft that canrotate about a rotational axis (A), a sliding cam device that can bedisplaced substantially parallel to the rotational axis (A) and has aperipheral extension portion on a circumferential surface, an actuatordevice that is designed to actuate or displace the sliding cam deviceand can undergo a second state change, a second measuring device that isdesigned to detect the second state change and is capable of determininga first angle of rotation α of the camshaft on the basis of the secondstate change, and the peripheral extension portion being designed toload the actuator device with at least one force component outwardlydirected and radial to the rotational axis (A).
 5. The arrangement asset forth in claim 4, wherein the actuator device has: a first couplingelement that is designed to intermittently load the sliding cam devicewith a force component substantially parallel to the rotational axis(A), which is designed for a change of position via a translationalmovement or a rotation in relation to a second longitudinal axis (B) ofthe actuator device, and a drive element that is designed tointermittently load the first coupling element with a force componentsubstantially perpendicular to the rotational axis (A).
 6. Thearrangement as set forth in claim 4, wherein the second measuring deviceis designed to detect the second state change or change of positionelectromagnetically, inductively, electrostatically, capacitatively oroptoelectronically, and wherein at least one of the following is true:is integrally formed with the drive element, and is embodied with a Hallsensor.
 7. The arrangement as set forth in claim 4, further comprisingat least one of the following: a first measuring device, wherein thefirst measuring device: is embodied with an electromagnetic, inductive,electrostatic, capacitative or optoelectronic sensor, is designed todetect a second angle of rotation β, a third angle of rotation ε or afourth angle of rotation ζ, is embodied with an ohmic sensor, inductivesensor, capacitative sensor, Hall sensor or with an optoelectronicsensor, and is an incremental encoder, a first angle measuring device,which is connected in a rotationally fixed manner to the camshaft, whichis designed to detect the third angle of rotation ε, and a second anglemeasuring device, which is connected in a rotationally fixed manner tothe crankshaft, which is designed to detect the fourth angle of rotationζ.
 8. The arrangement as set forth in claim 4, wherein the sliding camdevice has on a circumferential surface a guide groove arrangement withat least one guide groove, the guide groove arrangement being designedto guide the actuator device or the first coupling element thereofintermittently substantially in the manner of a slotted guide, the guidegroove arrangement being embodied with the peripheral extension portion,and the guide groove arrangement having two intersecting guide grooves.9. The arrangement as set forth in claim 4, with an adjustment mechanismthat is designed to set an angle-of-rotation position of the camshaftrelative to the crankshaft, and with a control device that is designedto control the adjustment mechanism on the basis of the second statechange, the change of position of the actuator device, the firstdifferential angle γ₁, the second differential angle γ₂ or the thirddifferential angle γ₃.
 10. A reciprocating piston engine with anarrangement as set forth in claim
 4. 11. A computer program containinginstructions, wherein the instructions, when they are carried out by acontrol device, cause the control device to execute a method as setforth in claim
 1. 12. A computer-readable medium, on which a computerprogram as set forth in claim 11 is stored.
 13. A method for determiningan angle of rotation of a camshaft of a reciprocating piston engine,comprising: providing the reciprocating piston engine with an actuatordevice, the camshaft, and a sliding cam device positioned substantiallyparallel to the camshaft, wherein the actuator device actuates byreversibly displacing the sliding cam device of the reciprocating pistonengine, feeding of actuation energy to the actuator device, whereuponthe actuator device undergoes a first state change, monitoring of theactuator device, detecting a second state change of the actuator device,determining of a first angle of rotation α of the camshaft of thereciprocating piston engine on the basis of the second state change ofthe actuator device, wherein the camshaft is connected in a rotationallyfixed manner to a first angle measuring device, detecting of a thirdangle of rotation ε of the camshaft with the first angle measuringdevice, and linking of the first angle of rotation α with the thirdangle of rotation ε at a second differential angle γ₂.
 14. The method asset forth in claim 13, wherein at least one of the following is true:the actuation energy is fed in electromagnetically, inductively orelectrostatically, the second state change is detectedelectromagnetically, inductively, electrostatically, capacitatively oroptoelectronically, the second state change is detected as a change ofposition of the actuator device, wherein the change of position is atranslational movement or rotation in relation to a second longitudinalaxis (B), and the first angle of rotation α is determined on the basisof a predetermined change of position of the actuator device.
 15. Themethod as set forth in claim 13, wherein the camshaft has an adjustmentmechanism that is designed to set an angle-of-rotation position of thecamshaft relative to a crankshaft, further comprising: setting of theangle-of-rotation position on the basis of a first differential angleγ₁, the second differential angle γ₂, or a third differential angle γ₃.16. A method for determining an angle of rotation of a camshaft of areciprocating piston engine, comprising: providing the reciprocatingpiston engine with an actuator device, the camshaft, and a sliding camdevice positioned substantially parallel to the camshaft, wherein theactuator device actuates by reversibly displacing the sliding cam deviceof the reciprocating piston engine, feeding of actuation energy to theactuator device, whereupon the actuator device undergoes a first statechange, monitoring of the actuator device, detecting a second statechange of the actuator device, determining of a first angle of rotationa of the camshaft of the reciprocating piston engine on the basis of thesecond state change of the actuator device, wherein a crankshaft of thereciprocating piston engine is connected in a rotationally fixed mannerto a second angle measuring device, detecting of a fourth angle ofrotation ζ of the crankshaft with the second angle measuring device, andlinking of the first angle of rotation α with the fourth angle ofrotation ζ at a third differential angle γ₃.
 17. The method as set forthin claim 16, wherein at least one of the following is true: theactuation energy is fed in electromagnetically, inductively orelectrostatically, the second state change is detectedelectromagnetically, inductively, electrostatically, capacitatively oroptoelectronically, the second state change is detected as a change ofposition of the actuator device, wherein the change of position is atranslational movement or rotation in relation to a second longitudinalaxis (B), and the first angle of rotation α is determined on the basisof a predetermined change of position of the actuator device.
 18. Themethod as set forth in claim 16, wherein the camshaft has an adjustmentmechanism that is designed to set an angle-of-rotation position of thecamshaft relative to the crankshaft, further comprising: setting of theangle-of-rotation position on the basis of a first differential angleγ₁, a second differential angle γ₂, or the third differential angle γ₃.